Lubricating compositions



LUBRHCATRNG GGMPGEHTIONS No Drawing. Appiica'iion .iune 15, 1956 Serial No. 591,535

it) Qiaims. (Ci. 25233.6)

This invention relates to novel lubricating compositions and, particularly, those suitable for lubricating solid surfaces at high temperatures. More specifically, the present invention pertains to new and improved lubricating oil compositions which are suitable for lubricating aircraft gas turbine engines, as well as other equipment normally operated at extremely high temperatures.

In our copending application Serial No. 490,676, filed February 25, 1955, now Patent No. 2,794,981, issued June 4, 1957, of which the present application is a continuation-impart, there are described essentially aromaticfree lubricating hydrocarbon oils containing a minor amount of a zinc, cadmium and/ or lead salt of a thiccarbamic acid. Lubricants of this type are excellent for lubricating aircraft gas turbine engines and similar equipment normally operating under extremely severe conditions such as at temperatures in the range of from below minus 65 F; to about 400 F. or even higher. However, it has been observed that lubricants of this type, although effective for the lubrication and protection of metal surfaces such as of steel, steel alloys, silver, cadmium and the like, cause, or at least permit, corrosion and pitting of copper surfaces. in aircraft engines or similar equipment this may eventually result in engine failure.

The art discloses various means of preventing corrosion of copper surfaces by lubricants such as those described in U. S. Patents 2,382,781, 2,151,300 and 2,146,543 and include as the corrosion inhibitors various phosphorusatent containing compounds such as organic phosphites, phosphorus-nitrogen compounds, sulfur-containing compounds, metal detergent compounds, and mixtures thereof. Under high loads and elevated temperatures the effectiveness of these materials as inhibitors of corrosion and pitting of copper surfaces has been found to be poor, particularly when in combination with a thiocarbamate.

It has now been discovered that such aromatic-free, essentially isoparamnic, hydrocarbon oils containing a minor amount of an oil-soluble cadmium dithiocarbamate methods, a preferred process involving isomerization of parafiin wax such as is described in U. S. Patents 2,668,- 866 and 2,668,790.

Waxes used in producing essentially aromatic-free isoparafiinic lubricating oils include commercial parafiin Waxes which consist largely of n-paraflinic hydrocarbons and some naphthenic and aromatic hydrocarbons. Waxes of this type originate from distillate oil fractions such as East Texas 250 distillate, which contains about straight-chain hydrocarbons covering the range from n-C to 11-C the balance being naphthenes and" aromatics. On isomerizing such waxes as described in the above patents and thereafter flash-removing the light ends, solvent dewaxing, and then topping to remove volatile compounds, the topped dewaxed isomerizate contains a substantial amount of non-paratiinic material, mostly alkyl aromatics formed by dehydrogenation of naphthenes in the original Wax, which must be removed by dearomatization. This may be done by suitable means, such as chemical (acid) treatment, solvent extraction, solid adsorption, or a combination of steps such as first solvent treating the oil to remove a portion of the aromatics and then treating the oil with solid adsorbents such as silica or silica-alumina gels or activated carbon to remove all of the aromatics and substantially all of the naphthenes, so that the product is essentially isoparaffinic in character. Oils of this type have a pour point of at least as low as 40 F. and preferably between 50 and 65 F., and molecular weights of at least 350 an preferably between 400 and 650.

An example of an essentially aromatic-free isoparailinic lubricating oil (X for use in compositions of this invention has the following properties:

API 41.1. Refractive index, il 1.4560. Moi. weight 456. Viscosity at 210 F 4.98. Viscosity at F 24.0. Viscosity index, F 147. Pour point, F -60. Cloud point, F 60. Flash point, F 460. Volatility, percent loss in 6%. hr. at 400 F 6.4. Monoaromatics Less than 0.15. Carbon, percent w 85.28. Hydrogen, percent w 14.69. Empirical formula C i-1 Naphthenicity One ring in approximateiy 15% of molecules.

The anti-oxidant oil-soluble cadmium dithiocarbamates include the cadmium N, or N,N-hydrocarbyl substituted dithiocarbamates wherein the hydrocarbyl radicals can be alkyl, or cycloalkyl radicals. it is preferred that the hydrocarbyl radicals be alkyl radicals of from 4 to 16 carbon atoms, and preferably from 4 to 12 carbon atoms.

illustrative examples of cadmium dithiocarbamates are cadmium dialkyldithiocarbamates such as cadmium dipropyl dithiocarbamate, dibutyl dithiocarbamate, diamyl dithiocarbamate, dihexyl dithiocarbamate, dioctyl dithiocarbamate, di-Z-ethylhexyl dithiocarbarnate, di-isobutyldithiocarbamate, diisoamyl dithiocarbamate, N-amyl-N'- methyl dithiocarbamate, N-methyl-i '-octyl dithiocarbamate, N-octyl-N'-butyl dithiocarbamate, N-n-an1yl-N- 2-methylbutyl dithiocarbamate, butyl dithiocarbarnate, N-octyl-N-2-ethylhexyi dithiocarbamate, and cadmium dicycloalkyl dithiocarbamates,

such as cadmium'dicyclohexyl dithiocarbamate, and the 7 like.

The cadmium salts taken singly or in mixtures can be used in amounts varying from about 0.05% to about 5% and preferably from about 0.1% to about 2% by weight, based on the total composition.

The other essential additive, which functions as an inhibitor or" pitting and corrosion of copper, is an oilsoluble halogen-containing organic phosphate or phosphonate; it can be'represented by the formula:

P-(O):R

wherein'at least one of the O-linked Rs is an aliphatic halohydrocarbyl radical and the other(s) R'is hydrogen, an aliphatic hydrocarbyl radical, or an aliphatichalohydrocarbyl radical, all O-linked Rs preferably being beta-chloroor bromo-alkyl radicals, and wherein the R which is bonded directly to phosphorus when x is zero, is an alkenylradical, x being an integer from zero to one.

Examples of halogen-substituted hydrocarbyl (alkyl, cycloalkyl, aralkyl) phosphates and 'phosphonates include haloalkyl phosphates such as trisQS-chloroethyl) phosphate, tris(B-chloro-Z-ethylhexyl) phosphate, butyl di cliloroe'thyl)phosphate, butyl di(B-chloroethyl)phosphate, cresyl diQQ-chloroethyl) phosphate, p-chlorophenyl di(B-chloroethyl)phosphate, S-chloroethyl diphenyl phosphate; tri(dichloropropyl) phosphate and mixturesthereof. Suitable haloalkyl alkneylphosphonates are represented by di(/3-chloroethyl) vinylphosphonate, dim-chlor'opropyl) vinylphosphonate and the alkyl haloa'lkyl vinylphosphonates, such as methyl fi-chloroethyl vinylphosphate, ethyl fi-chloroethyl vinylphosphonate, ethyl fS-chloropropyl vinylphosphonate, and the like. Mixtures of the phosphates and phosphonates are particularly desired where oil solubility'is. a problem andsuch mixtures are exemplified 'by trisQB-chloroethyl) phosphate and bisQS-chloroethybvinyl phosphonate, or tris(5-ch1oropropyl)phosphate and =bis(,8-chloroethyl)vinyl phosphonate.

The halogen-containing phosphorus compounds are used in amounts varying from about- 0.005% to about 2 and preferably from about 0.01% 'to about 0.5% by Weight based on the total-compositions.

To ensure good oxidation stability of compositionsof this invention at normal engine operating temperatures, minor amounts of an organic amine antioxidant can be added. Particularly effective materials are aromatic amines such as phenyl-alpha-naphthylamine, phenyl-betanaphthylamine and N,N,N',N-tetramethyldiamino-diphenylmethane. These amines, when used, are employed in amounts of from about 0.01% to about 2% by weight, basedon the total composition.

he following compositions are illustrative of preferred compositions of the invention:

Composition B: 7

Cd diamyldithiocarbamate 0.25 Cd di-2-ethylhexyldithiocarbarnate 0.25 Tris(fi-chloroethyl) phosphate 0.02

Bis(,6-chloroethyl) vinylphosphonate 0.05

Phenyl-a-naphthylamine 0.2 lsoparafiinic lubricating oil 1 (aromatic-free) Balance Composition C: a

Cd diamyldithiocarbamate 0.25 Cd di-Z-ethylhexyldithiocarbamate 0.25 TrisUi-chloroethyl) phosphate 0.01 Bis(,8-chloroethyl) vinylphosphonate 0.015 Phenyl-a-naphthylamine 0.25 Isoparafiinic lubricating oil 1 1 (aromatic-free) Balance Composition D:

Cd' diamyldithiocarbamate 0.25 Cd di-2- ethylhexyldithiocarbamate -0.4 Tris(B-chloroethyl) phosphate 0.01 Bis(fl-chloroethyl) vinylphosphonate 0.015 Phenyl-u-naphthylamine 0.1

Isoparaflinic lubricating oil 1 (aromatic-free) Balance Composition E:

Cd diamyldithiocarbamate 0.25 Cd 'di-Z ethylheXyIdithiocarbamate 0. 25 Tris(,B-'chloroethyl) phosphate "0.01 Bis(fl-chloroethyl) vinylphosphonate 0.015 Isoparaflinic lubricating oil 1 (aromatic-free) Balance Composition F: T

1 Oil '(X) 'asdeseribed in column 2.

aromatic-free isoparaflinic lubricating oil containing from 0.1 to 1% of Cd dibutyldithiocarbamate, .orCd dihexyldithiocarbamate; or Cd dicyclohexyldithiocarbamate, or Cd diamyldithiocarbamate, and from about 0.01% to 0.5% of 'tris(B-chloroethyl) phosphate, or tris Composition A:

' 7 Percent Cd diamylclithiocarbamate- 0.25 Cd di-Z-ethylhexyldithidcarbarnate 0.25 Tris(,B-chloroethyl) phosphate 0.01 Eis(,6-cltilo'r'oethyl) vinylphosphonate H 0.015 Phenyl-a-naphthylamine Q 0.l

'ilsop'arafiinic lubricating 'oil 1 I "(aromatic-free) Ba -nae phosphate, 'or tris( 3-bromoethyl) phosphate, bisQS-chloroethyl) vinylphosphonate, bis,(fi-brcmoethyl)v vinylphosphonate, bis(fl-lchlorophe'nyl) vinylphospho'n'ate andjniix' tures'thereof. To these compositions can be added from 0.1% to 1% of an amine antioxidant such asph'nyl anaphthylamine or phenyl-B-naphthylamine.

In order to demonstrate the effectiveness of compositions'of this invention in preventing pitting and corrosion ofpcopper surfaces as well as other metal'surfac'esftlie compositions identified below were subjectedfltotheMlL- 11-7808 oxidation-corrosion test described in Scientific Lubrication,1September 1954, volume 6, No.9,'page 2 4,

the results are shown in Tamer.

Other examples of this invention include'compositions I comprising anoil base of the type described, narnely, an.

TABLE I MIL-L-7808 oxidation-corrosion rest Metal Weight Loss, mg./c1n.= Viscosity Acid Increase, Neu Sludge, Composition Percent at N 0., Percent Cu Mg Fe Ag A1 100 F. Mg. w.

KOH/g.

(1) Oil X base containing 0.1% phenyl-a-naphthylamlne 0.1% Cd di2-etby1hexyl- Oil X base containing 0.1% (3) Di-2-ethylhexyl sebacatc base containing 5% trlbutyl phosphate 0.5% phenyl-fi-naphthyla-mine 0.5% N,N-

di-seo-butyl-p-phenylene diamine 0.5% phenothiazine.

(4) Dl-2-ethylhexyl sebacate base containing 6% tricresyl phosphate 0.5% phenothiazine 0.1% N,N-di-sec-butylp-phenylenediamine.

In the MIL-L-7808 bench tests, compositions A and B increased rubber swelling by only 0.3% and 1.1%, respectively, and were essentially non-corrosive to copper at 450 F. (0.62 and 0.36 nag/in? Cu, respectively) whereas compositions 1 and 4 increased rubber swelling by 27%, and were corrosive to copper (3.2 and 2.2 mg./in. Cu, respectively). Also compositions A and B did not pit the copper while with compositions 1 and 4 the copper surface was heavily pitted.

Other compositions of this invention which pass the MILL-7808 bench test include compositions B, C and D.

Compositions of this invention may contain minor amounts (0.01l%) of extreme-pressure agents, antiwear agents, color stabilizers, viscosity index and pour point depressants, and the like.

We claim as our invention:

1. A mineral lubricating oil comprising a major amount of an aromatic-free essentially isoparafiinic lubricating oil obtained by isomerizing a paraffin wax in the presence of hydrogen and an isomerizing catalyst at a temperature between about 300 C. and 550 C. and thereafter de aromatizing the oil and having incorporated therein from about 0.05% to about 5% of an oil-soluble cadmium dithiocarbamate and from about 0.05% to about 2% of an oil-soluble halogen-containing phosphorus organic compound having the general formula wherein at least one of the O-linked Rs is a chloro alkyl radical and any other O-linked Rs, are selected from the group consisting of hydrogen, allryl and chloroalkyl radical, said alkyl radicals having from 2 to 8 carbon atoms and wherein the R which is bonded directly to phosphorus when X is zero, is an allienyl radical, X being an integer from Zero to one.

2. A lubricating composition comprising a major amount of an aromatic-free essentially isoparaffinic lubrieating oil obtained by isomerizing a paraffin wax in the presence of hydrogen and an isomerizing catalyst at a temperature between about 300 C. and 550 C. and thereafter dearomatizing the oil and having incorporated therein from about 0.05 to about 2% of an oil-soluble cadmium dithiocarbamate and from about 0.05% to about 2% of a chlorine-containing C alkyl phosphate.

3. A lubricating composition comprising a major amount of an aromatic-free essentially isoparafiinic lubrieating oil obtained by isomerizing a paraffin wax in the presence of hydrogen and an isomerizing catalyst at a temperature between about 300 C. and 550 C. and thereafter dearomatizing the oil and having incorporated therein from about 0.05 to about 5% of an oil-soluble cadmium dithiocarbamate and from about 0.05% to about 5% of a chlorine-containing C alkyl phosphonate.

4. A lubricating composition comprising a major amount of an aromatic-free essentially isoparafiinic lubricating oil obtained by isomerizing a paraifin wax in the presence of hydrogen and an isomerizing catalyst at a temperature between about 300 C. and 550 C. and thereafter dearomatizing the oil and having incorporated therein from about 0.05% to about 5% of cadmium di-2- ethylhexyl dithiocarbamate and from about 0.05% to about 5% of a chlorine-containing C alkyl phosphate.

5. A lubricating composition comprising a major amount of an aromatic-free essentially isoparafiinic lubricating oil obtained by isomerizing a paraffin wax in the presence of hydrogen and an isomerizing catalyst at a temperature between about 300 C. and 550 C. and thereafter dearomatizing the oil and having incorporated therein from about 0.05% to about 5% of cadmium diamyl dithiocarbamate and from about 0.05 to about 5%, of a chlorine-containing C alkyl phosphate.

6. A lubricating composition comprising a major amount of an aromatic-free essentially isoparaidnic lubricating oil obtained by isomerizing a paraffin wax in the presence of hydrogen and an isomerizing catalyst at a temperature between about 300 C. and 550 C. and thereafter dearomatizing the oil and having incorporated therein from about 0.05 to about 5% of a mixture of cadmium diamyl dithiocarbamate and cadmium di-2- ethylhexyl dithiocarbamate and from about 0.05% to about 5%, of a chlorine-containing C alkyl phosphate.

7. A lubricating composition comprising a major amount of an aromatic-free essentially isoparafiinic lubricating oil obtained by isomerizing a parafiin wax in the presence of hydrogen and isomerizing catalyst at a temperature between about 300 C. and 550 C. and thereafter dearomatizing the oil and having incorporated therein from about 0.05% to about 5% of a mixture of oilsoluble cadmium diamyl dithiocarbamate and cadmium di-Z-ethylhexyl dithiocarbamate and from about 0.05% to about 2%, of a chlorine-containing C alltyl phosphonate.

8. A lubricating composition comprising a major amount of an aromatic-free essentially isoparafiinic lubricating oil obtained by isomerizing a parafiin Wax in the presence of hydrogen and an isomerizing catalyst at a temperature between about 300 C. and 550 C. and thereafter dearomatizing the oil and containing from 0.01% to 10% of a mixture of cadmium diamyl dithiocarbamate and cadmium di-Z-ethylhexyl dithiocarbamate and from 0.001% to 1% of a mixture of tris( 3-chloroethyl) phosphate and bis(;?-chloroethyl)vinyl phosphonate.

9. A composition of claim 8 containing from 0.01 to 2% of an aromatic amine.

10. A lubricating composition comprising a major amount of an aromatic-free essentially isoparafiinio-lubrieating oil obtained by isomerizing a paraflin wax in the 0 presence of hydrogen and an isomerizing catalysjtfat aft, temperature between about 300 C. and 550' C. and thereafter dearomatizing the oil and containing about" 0.25% each of cadmium diamyl dithiocarbamate and'cad mium di-Z-ethylhexyl dithiocarbamate, about 0.01% each of trisQS-chloroethyl) phosphate and bis(,8-ch1or'oethyl)-' vinyl phosphonate, and about 0.1% phenyl-qz-naphthyh' amine.

l leferencesi the file of this patent UNITED STATES PA TENTS 7 'Greatj'Britain Nov. 7

gt t !i t".""f Sullivan Sept. 26, 1939 --"t-.'?:"-.-t-----. D 9! 1941 Knutson ettal. Feb 1," -1944 "Clayton Oct. 5, 1948 -Good- Feb. 9, -1954 Good Feb. 9, ,1954

FOREIGN: PATENTS i V 

1. A MINERAL LUBRICATING OIL COMPRISING A MAJOR AMOUNT OF AN AROMATIC-FREE ESSENTIALLY ISOPARAFFINIC LUBRICATING OIL OBTAINED BY ISOMERIZING A PARAFFIN WAX IN THE PRESENCE OF HYDROGEN AND AN ISOMERIZING CATALYST AT A TEMPERATURE BETWEEN ABOUT 300*C. AND 550*C. AND THEREAFTER DEAROMATIZING THE OIL AND HAVING INCORPORATED THEREIN FROM ABOUT 0.05% TO ABOUT 5% OF AN OIL-SOLUBLE CADIMUM DITHIOCARBAMATE AND FROM ABOUT 0.05% TO ABOUT 2% OF AN OIL-SOLUBLE HALOGEN-CONTAINING PHOSPHORUS ORGANIC COMPOUND HAVING THE GENERAL FORMULA 